1. Field of the Invention
This invention pertains to a refrigeration compressor, and more particularly to a direct suction radial compressor wherein incoming refrigerant is fed directly through the compressor housing to a centrifuging assembly which separates the liquid refrigerant and oil from the gaseous refrigerant, which is then delivered to cylinders to be compressed.
2. Description of the Prior Art
In a typical refrigeration compressor, incoming refrigerant is drawn into the compressor housing to be ultimately compressed and then subsequently discharged from the compressor for further use in the refrigeration process. During the period of time the refrigerant is within the compressor housing, several undesirable effects occur. Upon being admitted into the compressor housing, the refrigerant is heated by the heads and motor causing the entrained oil within the refrigerant to be delivered to the sump in the bottom of the compressor.
One undesirable effect apparent from the above heating of the suction gas is the increased work output required of the motor to drive the piston-cylinder arrangement. The work required from the motor to drive the piston-cylinder arrangement to compress the refrigerant is directly proportional to the pressure differential and the volume of the gas in the cylinders. The refrigeration effect is directly proportional to the mass rate of the refrigerant being compressed. For a given cylinder volume, the mass rate will be diminished by any increase in the suction gas temperature. Therefore, a consequence of allowing the refrigerant to be superheated within the compressor housing is less efficient operation of the compressor.
Another undesirable result from allowing the refrigerant to be superheated within the compressor housing is the raising of the temperature of the oil entrained within the refrigerant. Because the refrigerant enters the cylinders at a higher temperature, upon being compressed, the refrigerant has a discharge temperature much higher than if it entered the cylinders at a lower temperature. This higher refrigerant discharge temperature increases the temperature of the lubricating oil, thereby reducing the lubricating properties of the oil and causing premature failure of bearings, wrist pins and the like.
Another type of refrigerant compressor which is commonly utilized is a rotary compressor in which the refrigerant is fed directly into the cylinder. Since this type of refrigeration compressor does not initially draw the refrigerant into the compressor housing to separate the oil and cool the motor, an alternate method must be used to accomplish these requirements. That method comprises discharging the compressed high pressure refrigerant from the cylinder to the housing so that expansion of the refrigerant may occur to separate the oil and cool the motor. This method of oil separation and motor cooling is undesirable in heat pump applications where compression ratios frequently reach excessive levels. High compression ratios result in very high discharge temperatures which reduce motor cooling and generate oil temperatures that reduce lubricity. Under some operating conditions, excessive quantities of refrigerant in high pressure oil reduce lubricity with resulting bearing failures.